so i just bought a gx160 14cc head and 1.3 billet ratio rocker arms from AGK and it seems like the stock push rods aren't long enough to even come in contact with the rocker arms (rocker arms screwed all the way down) do these 1.3 billet ratio rocker arms require longer pushrods? or what....?:censure:
Without knowing what all your parts are it is impossible to diagnos; you said billet rockers, do you mean the billet roller rockers? I'm running the 1.3 roller rockers in my AGK engine! The owner of AGK is Shane, he is a great guy and you should call him and ask him, he knows what parts you have! 1.3 rockers are dicey, you need to be real cautious about clearance problems; rocker to valve cover as well as valve to piston!
Wonder what cam and springs you are using?? With 1.3's you need to be careful! 18 lb springs will coil bind, while 26's require a hardened cam!
Shane & I are friends and I sent him the link to this thread -
Wonder what cam and springs you are using?? With 1.3's you need to be careful! 18 lb springs will coil bind, while 26's require a hardened cam!
Shane & I are friends and I sent him the link to this thread -
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The billet rocker arms come from Burris. I talked to them earlier in the week about the installation of the rocker arms. We are not sure if the instructions were missing from some of these rocker arm kits, however in the instructions it says you need to mill down the rocker stud posts about .120". In most applications, if you do not mill down the rocker stud posts, the stock length valves and pushrods will fall short of reaching the rocker arms.
When Burris first came out with these rocker arms there wasn't much informaion available. We called and asked before we decided to carry them in our store and they were supposed to be more of a bolt-in and go product. As with any new product there were issues in certain applications that required some changes to be made in order for the rocker arms to work.
The professional engine builders we work with always say no part is a bolt-on part in a modified motor. Everything needs to be drilled, ground down and/or cut in order to fit. Although we don't think that is entirely true, we do understand this is why engine builders get paid to build engines. They will do what needs to be done in order for all the aftermarket parts to work together properly.
Here is a copy of the instruction...
GXC-420-00
GX 200 Honda/Clone Billet Rocker Arm Kit
Thoroughly clean and inspect the components. Apply a small
amount of Blue Loctite to the supplied rocker studs and install
the guide plate (with the champhered holes facing up) and
torque them to 120 in/lbs. Assemble the rockers and apply
assembly lube to all contact surfaces and set the lash to .004”
min. (any tighter will reduce the contact running clearances and
prevent oil from entering!) When setting the lash it is not
necessary to use Loctite on the adjuster nut or set screw. Run
the engine for a short session or warm up and re-set the lash
and you’ll be good to go.
Note the photo below. On some engines with the short OEM
valve length the rocker adjuster nut runs out of tightening
range and it may be necessary to shorten the rocker stud posts
to accommodate this. About .12” is the maximum removal
before the stud will bottom out.
Caution!! When installing the rocker arm studs care
should be taken to clean the 8mm threads in the
stud bosses of any contamination especially dried
thread locking compounds such as Loctite. If necessary
run a 8X1.25mm tap in to the hole to clean the
threads so the stud can tighten up against the guide
plate without forcing it otherwise damage or breakage
to the stud may occur.
When Burris first came out with these rocker arms there wasn't much informaion available. We called and asked before we decided to carry them in our store and they were supposed to be more of a bolt-in and go product. As with any new product there were issues in certain applications that required some changes to be made in order for the rocker arms to work.
The professional engine builders we work with always say no part is a bolt-on part in a modified motor. Everything needs to be drilled, ground down and/or cut in order to fit. Although we don't think that is entirely true, we do understand this is why engine builders get paid to build engines. They will do what needs to be done in order for all the aftermarket parts to work together properly.
Here is a copy of the instruction...
GXC-420-00
GX 200 Honda/Clone Billet Rocker Arm Kit
Thoroughly clean and inspect the components. Apply a small
amount of Blue Loctite to the supplied rocker studs and install
the guide plate (with the champhered holes facing up) and
torque them to 120 in/lbs. Assemble the rockers and apply
assembly lube to all contact surfaces and set the lash to .004”
min. (any tighter will reduce the contact running clearances and
prevent oil from entering!) When setting the lash it is not
necessary to use Loctite on the adjuster nut or set screw. Run
the engine for a short session or warm up and re-set the lash
and you’ll be good to go.
Note the photo below. On some engines with the short OEM
valve length the rocker adjuster nut runs out of tightening
range and it may be necessary to shorten the rocker stud posts
to accommodate this. About .12” is the maximum removal
before the stud will bottom out.
Caution!! When installing the rocker arm studs care
should be taken to clean the 8mm threads in the
stud bosses of any contamination especially dried
thread locking compounds such as Loctite. If necessary
run a 8X1.25mm tap in to the hole to clean the
threads so the stud can tighten up against the guide
plate without forcing it otherwise damage or breakage
to the stud may occur.
In case anybody is buying these: I just ran into this problem too. Have to take the stud boss down to get to work. Pisses meoff since I called Burris before i bought these and asked them if I would need to do it on stock head, valve, and pushrods. Right now Im thinking about running them without the guide plate until I can get the stud posts milled. anybody do this?
Please keep in mind there are many variables that affect the installation of our billet 1.3/1 rockers in a GX/Clone and since these are up to the individual doing the mods we can't have an instruction sheet that would come close to covering it. Those variables include block and head milling, overall valve length and push rod length and minor differences in the different brands of engines. As heads and blocks get milled and valves and pushrods get longer the farther away the rocker moves farther up the stud. If you are using them on a stock engine without any or all of these mods then out stamped 1.3/1 rockers are the ticket.
Regards, Burris Racing
Regards, Burris Racing
Yes, I understand all that. Not too big a problem; i was just rushing to get a bike ready for Saturday drag races. I just wonder how often the mods are required for these rockers. I supect more often than not since the guide plate is about .100 thicker than the Honda guide plate. I milled .060 off Burris one and it almost worked but I didn't have enough time to do more work on it. I fully understand that there is no guarantee that anything will fit a modified engine such as mine so no hard feelings. I do have stock length valves, lifters, and pushrods though. I think I will just mill the posts and get another guide plate from you guys. or maybe use a Honda guide plate if the loads are not significant. One thing I appreciateis that you guys got htese out in a hurry for me, even if it all didn't work out. Glad to see you are taking an interest in the Mini Bike community too.
It seems to make the stock push rods work with the Burris rockers you need a stock guide plate modified to work, or your head needs to be milled about 0.100" plus block decked about 0.050".
Or you can buy Animal billet lifters, or longer custom length push rods.
But there should be a warning before buying them. I built Korndogs motor. The block deck has been surfaced flat, and head milled 0.050" and the stock length HD push rods are still to short with that HD guide plate under the rockers.
Or you can buy Animal billet lifters, or longer custom length push rods.
But there should be a warning before buying them. I built Korndogs motor. The block deck has been surfaced flat, and head milled 0.050" and the stock length HD push rods are still to short with that HD guide plate under the rockers.
Charles, longer lifters or pushrods would lift the back of the rocker and move the adjuster nut up but would leave that tail end of the rocker sticking up much higher than the tip where it contacts the valve and most likely the tip will move off the end of the valve during opening (and lose lift!). The pushrod side of the rocker in a closed position (with longer lifters or push rods) would most likely start out in the position (about 2 o'clock) where it should be at full open. This situation doesn't have an easy answer simply because the rest of the components aren't matched like they would be in the YF200 R1 Yamaha valve/rocker kit which make it a bolt in. We could do the same with the GX/Clone but it ain't cheap! lol
Picasa Web Albums - BNSS/F200 - YF Yamaha GX/...
Picasa Web Albums - BNSS/F200 - YF Yamaha GX/...
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so, just to be sure; we need to lower the fulcrum to accomodate the endplay at the pushrod without affecting the placement of the rocker tip on the valve. Can we safely take the maximum .150 off the post without affecting operation of the rockers? Is that recommended? Have you seen any endplay with stock pushrods, valves closed with the maximum amount of material removed from posts?
The underlying issue is the billet rockers were made for longer valves and (most likely) longer pushrods and other engines so in this specific case some mods or changes have to be done to get them to work. Longer valves allow springs that have larger coils and function better and also reduce the chance of interference between the retainer and guide at higher lifts. We have longer stainless valves (with the proper retainers and split locks) in 24, 25, 27.3 and 30 mm diameters and 5.5mm stems and longer pushrods. keep this in mind if you decide to go this way.
Frankly, I figured i would save the 50 bucks on what a pair of Raeseng or Hunters cost. No offense but I am not going to start replacing valves to accommodate these rocker arms. I don't think I will be floating my 55# springs and banging the retainer into the guide either, but I guess anything is possible. I know people who run these rockers and have had good luck with them, but .......